~,which~ or ~and~ Which commly used?

My name is Yuya Maruyam. I'm Hosei University student.
I want native English speakers to ask some questions.
⑴ Which is more commnly used, "~,which~"or"~and~" in spoken language?
For example, "I have a brother, who loves baseball." or "I have a brother and he loves baseball."
⑵ As with ⑴,how about in written language?